Alaska Species Explorer

Smooth Lumpsucker

Common Name: Smooth Lumpsucker
Scientific Name: Aptocyclus ventricosus
Size: Up to 41 cm (16 inches)

North Pacific, Bering Sea east to Sea of Okhotsk and south to Aleutian Islands and southeast Alaska; over continental shelf and slope. Sea surface to 1000 meters.


Adults are pelagic, migrating into rocky intertidal habitats to breed.

Life History:

Adult males guard the eggs that are laid in shallow/intertidal waters secured to a rock or other substrate.  Large eggs produce well developed larvae that are over half a centimeter long and resemble a tadpole.  The sucker disk fully functional upon hatching.  Little is known about their pelagic life. 

Diet in the Wild:

Zooplankton including ctenophores, jellyfish and copepods.

Natural Predators:

Bony fish, sable fish and cod, and some marine mammals including sea otters.

Population Status:

This species is encountered at a much higher rate in the spring when they concentrate in near shore waters to breed.  There is some evidence that this annual influx might be part of larger, multi-year cycle of species abundance.

Additional Information:

This is the only known species within the genus Aptocyclus.  There are however many other species of lumpsuckers, family Cyclopteridae, found in the north Pacific including the Pacific spiny lumpsucker, Eumicrotremus orbis, and toad lumpsucker, E. phrynoides.

Fun Facts:
  • Smooth lumpsuckers are among a small percentage of fish that do not have scales.